So, I'm curious how this will compete with free offerings like Flurry which do similar-ish mobile analytics tracking and can handle millions of users per app for free. I got very excited about this Heap announcement but looked at the pricing. Multiple thousands/month for sub-million unique users may be considered steep (but then again I'm a cheap developer). I've been looking for a Flurry alternative (since I just want analytics and none of their ad junk).

Mobile apps are kind of a different beast from websites. Apps can have huge number of unique users, whereas SaaS websites tend to have many fewer users by comparison.